Javascript Chrome有一项功能，可以在释放空格键时关闭警报框。如何创建在释放空格键时保持打开状态的警报框？

比如说。我想在按下空格键时打开警报。但是chrome在空格键上关闭了盒子

document.onkeydown = function(event) {
  var key_press = String.fromCharCode(event.keyCode);
  var key_code = event.keyCode;

  if(key_code == "32") {
     alert("Space-bar was pressed");
  }
}

---

改用document.onkeyup

document.onkeyup = function(event) {
  var key_press = String.fromCharCode(event.keyCode);
  var key_code = event.keyCode;

  if(key_code == "32") {
     alert("Space-bar was pressed");
  }
}